The new tornado terror zone: Why Dixie Alley's deadly twisters are stirring up more attention

By Kimberly Miller The Palm Beach Post

Friday

Mar 8, 2019 at 5:45 PMMar 8, 2019 at 5:45 PM

As the skies mustered their worst over the southeast last week, flocks of weather balloons from Texas to Tallahassee searched for signs of combustion in an atmosphere unhinged.

The helium army launched from universities and federal labs joined the traditional regimen of National Weather Service balloons as part of an effort to better understand the killer tempests in America's lesser-known tornado zone of Dixie Alley.

Additional readings on humidity, temperature and wind direction from terra firma through 100,000 feet were used by Storm Prediction Center forecasters during a 48-hour period before and during the March 3 melee. In Louisiana, the extra data showed where detonation was building and helped accurately shut down one watch area before Atlanta was put on edge.

The project, called Vortex Southeast, or Vortex SE, launched in 2016 as a congressional mandate with a budget of about $5 million annually.

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While the Great Plains may have more glamorous twisters, the night-stalking tornadoes of Louisiana, Alabama, Mississippi, Tennessee, Georgia and Florida's Panhandle can be more daunting to forecast and more deadly.

"Our storms are messier with other showers in and around them. They aren't distinct entities like they are many times over the Great Plains," said University of Alabama professor Kevin Knupp, who is working with several Vortex SE studies. "Our trees and topography and low cloud base make it challenging to observe tornadoes and that was particularly true last Sunday."

Twenty-three people died in the March 3 tornado outbreak. As of Friday, 34 tornadoes had been confirmed across Alabama, Florida's Panhandle, Georgia and South Carolina. One tornado tracked for 69 miles as first an EF-3 then an EF-4 with 170-mph winds.

In Florida, a rare EF-3 spinning with a 140-mph force touched down northeast of Tallahassee, destroying two homes, tossing cars and snapping power poles. Just 39 tornadoes of EF-3 ferocity have been recorded in Florida between 1954 and 2017, according to the Tornado History Project.

"We know when an environment across a state-size region is vulnerable, but what really determines what makes one county a target is a huge challenge," said Erik Rasmussen, the coordinating scientist for Vortex SE and senior research scientist at the Cooperative Institute for Mesoscale Meteorological Studies at the University of Oklahoma.

Tornado alley travels east

In its third year, the project is focusing on how pockets of slightly warmer air and topography, such as a downslope winds from Alabama's Sand Mountain, may play a role in tornado formation. Construction limitations — no one has basements, mobile homes are common — and how people react to storm alerts are also under examination.

The project may be even more important as some studies have found a decades-long shift in tornadic activity to the east, Rasmussen said.

At least two recent reports found tornado activity has decreased in the traditional Tornado Alley, while Dixie twisters are happening more often.

Purdue University researchers published findings in 2016 that showed the highest grouping of tornadoes between 1954 to 1983 occurred in southeastern Oklahoma and northeastern Texas — the "classical well-known center of Tornado Alley."

Between 1984 and 2013, that maximum activity had moved to northern Alabama.

Another report published in October in the online journal Climate and Atmospheric Science said everywhere east of the Mississippi River, excluding the west coast of the Florida peninsula, is experiencing more tornadoes. Although the reason is unclear, authors Vittorio Gensini and Harold Brooks said human contribution to a warming planet could be to blame.

Southeast Florida is rarely affected by tornadoes spawned by low pressure systems moving east across the mid-latitutdes, such as those on March 3, but can get whacked by tropical cyclone-created twisters or those that spin up in isolated violent thunderstorms.

"As the climate sloshes around, which it does, you would expect the more tornado-prone regions to change," Rasmussen said. "Vortex SE is much more rapid response than traditional science, and it's by necessity."

Firehose of humidity

Weather balloons started launching from Texas A&M University on Saturday as part of Vortex SE and under the guidance of atmospheric sciences assistant professor Christopher Nowotarski.

College Station, Texas, is hundreds of miles west of where the first tornadoes would hit Sunday, March 3 but the data from upper atmospheric samplings of wind speeds and direction fed into models forecasting what was coming.

The balloons launched every six hours for 48 hours. Across all of Vortex SE sites and National Weather Service offices, more than 200 balloons flew for the March 3 event.

"We were observing the development of the low pressure system and then it really intensified," Nowotarski said. "Our balloons were picking up on the upper-level wind patterns."

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Still, temperatures were cool on Sunday, not great tornado weather, although forecasters were warning for days severe weather was possible.

Then the counter-clockwise swirl of low pressure deepened, it dragged up humidity and heat from the Gulf of Mexico and lit a fuse to the westerly winds roaring high overhead.

"It really amazed me how quickly we got that low level warmth and moisture into southern Alabama and that really made the atmosphere conducive for tornadoes," Nowotarski said. "The models were showing it. We were a little skeptical, but then it happened."

In the Great Plains, fringe mountains running north and south provide more specific locations where air masses meet and tornadoes form. Storms also shut down about 9 p.m. as the air rapidly cools, Rasmussen said.

There's more chaos in the atmosphere in the southeast, which can also get a persistent firehose of humid air from the Gulf of Mexico.

Alabama, where 23 people were killed in a matter of minutes March 3, has the highest number of average annual tornado deaths in the U.S. Between 1985 and 2014, 14 people died in an average year in Alabama. In 2011, a tornado that roared in the vicinity of Tuscaloosa and Birmingham was a violent EF4 multiple-vortex with winds of 190 mph that killed 64, including six University of Alabama students. It caused approximately $2.4 billion in damage.

Florida's 30-year annual average of tornado deaths is three.

Tornadoes on Twitter but nowhere to go

The Vortex SE project is is the third to carry the Vortex name, which is an acronym for the Verification of the Origins of Rotation in Tornadoes Experiment. It is being overseen by the National Oceanic and Atmospheric Administration's Severe Storms Laboratory in Norman, Okla.

Each year, about 25 scientists decide what the most-pressing tornado-related questions are and ask for research proposals aimed at solving them.

The questions are usually a mix of science and behavioral queries about how tornado threats are communicated.

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After deadly tornadoes struck Georgia in January 2017, National Center for Atmospheric Research scientist Julie Demuth spent time interviewing survivors in mobile home parks as part of a project with Vortex SE.

Demuth said people were well aware of the storm. They got information on social media, from television, and with National Weather Service alerts. And they knew the difference between a watch and warning.

"The real issue is people feel they have no safe place to go," Demuth said. "People were asking if they should go to the Walmart, or the church, and if they go to the church, can they stay if they aren't members."

Demuth said there is often a false belief that people injured or killed were complacent or didn't understand the danger, when really it was a lack of a safe place to shelter.

"Certainly in the Midwest we all had basements," she said. "They don't."

Kmiller@pbpost.com

@KmillerWeather

This story originally published to palmbeachpost.com, and was shared to other Florida newspapers in the GateHouse Media network.

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